The nicotinic acetylocholine receptor (AChR) from mammalian skeletal muscle is purified by alpha-cobratoxin biospecific adsorption, ion exchange chromatography, and gel filtration. The subunit composition is determined by sodium dodecyl sulfate of anti-AChR IgG in a pool of 40 myasthenic patients from the University of Alabama in Birmingham School of Medicine Myasthenia Clinic. The patients are being examined both clinically and for anti-AChR antibody over time to determine the correlation between clinical severity and antibody titers. We are, in addition, studying the molecular interaction between individual IgGs from myasthenic patients with the AChR to better understand the heterogeneity of the immune response and also to attempt to localize antibody binding sites on the AChR.